Perfluorocyclic ether polymers



United States Patent 3,418,302 PERFLUOROCYCLIC ETHER POLYMERS Robert Albert Darby, Vienna, W. Va., assignor to E. I.

du Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware No Drawing. Filed Aug. 30, 1963, Ser. No. 305,837

' 5 Claims. (Cl. 260-875) The present invention relates to perfluorocyclic ether resins obtained by the polymerization of a fluorocarbon divinyl ether.

The polymerization of a vinyl compound normally proceeds through the opening of the double bond and addition to a growing polymer molecule without affecting the remainder of the molecule. In the polymerization of vinyl compounds, which contain two unsaturated groups, one or both vinyl groups will enter into the reaction depending on the nature of the compound. Where both double bonds are polymerized a crosslinked material is obtained while if only one double bond is reacted, an unsaturated resin is obtained. The formation of linear substantially saturated polymers from compounds containing two double bonds is therefore extremely unusual.

In accordance with the present invention, it was discovered that perfluorodimethylene-bis(periluorovinyl ether) when polymerized in certain ways gives rise to polymers having structures of the class consisting of:

CF CF-CFCF O and CF2CF2 and no measurable unsaturation as determined by infrared spectroscopy. The two isomeric cyclic structures result through a bond being formed between the carbon atom of one of the vinyl groups which is attached to an oxygen atom with either carbon atom of the other vinyl group. Both structures are formed during polymerization.

The polymerization of perfluorodimethylene-bis(perfiuorovinyl ether) can be controlled to result in the intramolecular cyclization by polymerizing the divinyl ether in dilute concentrations, e.g., in the presence of a liquid medium. The intramolecular cyclization also occurs when the divinyl ether is copolymerized with other monovinyl compounds in the presence of an inert liquid diluent. Particularly preferred comonomers comprise perfluoroalkyl perfiuorovinyl ethers having the formula:

where R, is a perfiuoroalkyl radical of one to twelve carbon atoms, perfluoroolefins having the formula:

where X is fluorine or the perfluoromethyl radical and perfiuorovinyl perfiuoroalkoxy ethers having the formula:

where X is fluorine or the perfiuoromethyl radical and m is a number from 1 to 4. Specific examples of suitable comonomers include perfluoromethyl perfluorovinyl ether, perfiuoropropyl perfluorovinyl ether, tetrafluoroethylene, hexafluoropropylene, and perfiuoro-Z-propoxypropyl perfluorovinyl ether.

The polymerization is preferably carried out in an inert liquid medium and in particular in an inert perfluorocarbon solvent. Suitable solvents include perfluoroheptane, perfiuorocyclohexane, perfiuorodimethylcyclobutane, perfluorobenzene, perfiuorodioxane, perfiuorotriethylamine, perfluoro-1,3,5-trimethylhexene-3, and perfluorol,2-di(methoxy)cyclobutane. The initiator employed for the polymerization of perfiuorodimethylene-bis(perfiuoro- 3,418,302 Patented Dec. 24, 1968 vinyl ether) can be any compound giving rise to free radicals but is preferably a perfluorinated initiator such as a perfiuoroperoxide or perfiuoroazo compound or a compound containing an N-F bond. In addition, ultraviolet-light can be used as a free radical initiator. The polymerization temperature can be varied widely and is not critical, but should be high enough to allow the decomposition of the particular initiator compound employed, and should be low enough to avoid excessive rearrangement of the II C F2=C F O to F C-O Frgroups Since the divinyl ether is liquid, polymerization is normally'carried out at atmospheric pressure, although higher pressure may be advantageously employed where the comonomer is gaseous at the polymerization conditions.

The formation of the polymeric materials of the present invention is further illustrated by the following examples:

EXAMPLE I In a glass carius tube were charged 2 g. of perfiuorodimethylene-bis(perfiuorovinyl ether) and 18 g. of perfluorodimethylcyclobutane. The tube was cooled to -80 C., evacuated, and charged with 3 mole percent N F based on monomer. The tube was sealed and allowed to stand at 25 C. for 24 hours. The gel so formed was dried in vacuo at 100. The resulting granular polymer could be pressed to a clear, stiff, tough film at 250 and 30,000 p.s.i. The polymer was found to contain no unsaturation as measured by infrared analysis.

EXAMPLE II In a platinum tube sealed at one end were placed 0.5 ml. of perfiuorodimethylene-bis(perfluorovinyl ether), 0.27 g. of tetrafluoroethylene, 4 ml. perfiuorodimethylcyclobutane and 0.02 ml. of 2,3-bis(difluoroamino)perfluoro-Z-butene. The charge consisted of equimolar amounts of tetrafluoroethylene and perfluorodimethylene bis(perfluorovinyl ether). The platinum tube was sealed, placed in a shaker tube, and pressured to 900 atm. with nitrogen. It was then heated to C. for 3 hours. A quantitative conversion to a copolymer of approximately 1/1 composition was obtained. This polymer could be pressed to a clear, stiff, tough film at 250 and 30,000 p.s.i. The polymer was free from unsaturation.

EXAMPLE III Into a Pyrex carius tube are placed 4 g. of perfluoromethyl perfluorovinyl ether, 2 g. of perfiuorodimethylenebis(perfiuorovinyl ether) and 14 g. of perfiuorodimethylcyclobutane. The tube is cooled to C. and 3 mole percent of N F based on monomer is added. The tube is sealed and allowed to stand at 25 C. for 24 hours. A solid copolymer of perfluoromethyl perfluorovinyl ether and perfluorodimethylene-bis(perfluorovinyl ether) is obtained.

Using the techniques illustrated, similar copolymers of the perfiuoromethylene-bis(perfluorovinyl ether) are also prepared with the comonomers not specifically illustrated but included in the foregoing description.

The polymers of the present invention are high molecular weight solid thermoplastic resins which can be fabricated into film, fiber, and other shaped articles by melt extrusion, and injection molding. The polymers of the present invention have outstanding chemical and thermal stability and superior electrical properties. Hence, the polymers in film form or in other forms are extremely useful insulating materials. The polymer can further be employed in other uses heretofore developed for fluorocarbon resins.

3 I claim: 1. A substantially saturated solid thermoplastic polymer of perfiuorodimethylene-bis(perfluorovinyl ether) containing structures of the class consisting of:

2. A substantially saturated solid thermoplastic homopolymer of perfluorodimethylene-bis(perfiuorovinyl ether) containing structures of the class of:

3. A substantially saturated solid thermoplastic copolymer of perfiuorodirnethylene-bis(perfiuorovinyl ether) and a perfluoroolefin having the structure of CFFCFX where X is selected from the group consisting of fluorine and the perfluoromethyl groups, said copolymer containing structures of the class consisting of:

Fz-C FC F-C F1- 0 Fz-C F-C FzC F- O O and O C 2 F4--(|) Cz F4 4. A substantially saturated thermoplastic copolymer of perfluorodimethylene-bis(perfluorovinyl ether) and a perfiuorovinyl ether having the formula:

where R is a perfiuoroalkyl radical of one to twelve carbon atoms, said copolymer containing structures of the class consisting of:

where X is selected from the class consisting of fluorine and the perfluorornethyl groups and m is an integer of one to four, said copolymer containing structures of the class consisting of:

CFz-CFCFCF2 dCFCF:OF-CF2 an o o C-CaF4-O References Cited UNITED STATES PATENTS 3,162,622 12/1964 Aldrich 260-875 JOSEPH L. SCHOFER, Primary Examiner.

J. A. DONAHUE, JR., Assistant Examiner.

US. Cl. X.R. 2609l.l

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION December 24, 1968 Patent No. 3,418,302

Robert Albert Darby It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, lines 5 to 8, the left-hand formula should appear as shown below:

line 18, cancel "of". Column 4, lines 16 to 19,

same column 3,

d appear as shown below:

the left-hand formula shoul -CF2-CFCF-CF2- Signed and sealed this 7th day of April 1970.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Attesting Officer 

1. A SUBSTANTIALLY SATURATED SOLID THERMOPLASTIC POLYMER OF PERFLUORODIMETHYLENE-BIS (PERFLUOROVINYL ETHER) CONTAINING STRUCTURES OF THE CLASS CONSISTING OF: 